<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
    <p>{{ username }}</p>
</div>
<script src="./lib/vue-2.6.12.js"></script>
<script>
    const vm = new Vue({
        data: {
            username: 'admin'
        }
    })
    vm.$mount('#app')
</script>
</body>
</html>